For Germa... something I noticed in OP for nobles and royals, blonde is prevalent. While for the D. Clan, black while not always is prevalent. This is interesting because of what Blonde/Yellow represent in fictional archetypes.
Blonde being light and good while black is dark and evil. The Vinsmokes, Doffy, many CDs are all blonde or would have been blonde in the siblings case. The supposedly good of the world. The D Clan the supposedly evil ones to the WG are black haired. So even though Oda is telling us WG bad, D Clan heroes. ...could it be a red herring and the WG are actually good or at least old Germa?